CVE-2026-66619

The Newsletters WordPress plugin before version 4.17 does not perform any nonce or capability check when saving one of its settings screens, and writes every submitted parameter into its own options. This allows attackers to make a logged-in administrator overwrite arbitrary plugin settings, including the credential protecting its API, via a Cross-Site Request Forgery attack.

The Newsletters WordPress plugin before version 4.17 does not generate its API key using a sufficiently random source, deriving it from a publicly known value. This allows unauthenticated attackers to compute the key and perform privileged actions such as adding and deleting subscribers and sending emails, when the optional API has been enabled.

The Newsletters plugin for WordPress up to version 4.17 is vulnerable to authorization bypass. Authenticated attackers with author-level access and above can send arbitrary newsletter emails to users of any WordPress role, including administrators, by forging POST fields during a normal post submission. The attacker can supply a role slug via the newsletters_mailinglistsroles POST field, enabling unauthorized mass-mailing and potential phishing.

The Newsletters WordPress plugin before version 4.16 does not strictly compare its API authentication key, allowing unauthenticated attackers to bypass the API authentication via type juggling and perform privileged actions such as modifying subscriber records and sending emails, when the optional API has been enabled.

The Newsletters WordPress plugin before version 4.16 does not restrict the classes allowed when unserialising a value taken from a public form submission, allowing unauthenticated attackers to inject arbitrary PHP objects.

The Newsletters plugin for WordPress (versions up to 4.14) is vulnerable to reflected XSS. Improper input neutralization during web page generation allows injection of malicious scripts.

The Newsletters plugin for WordPress up to version 4.13 is vulnerable to time-based SQL injection via the 'wpmlsubscriber_id' parameter. Insufficient escaping and lack of proper SQL query preparation allow unauthenticated attackers to append additional SQL queries, potentially extracting sensitive information from the database.